Spectrophotometric simultaneous determination of nickel, cobalt and copper by orthogonal signal correction–partial least squares

A method for the simultaneous spectrophotometric determination of nickel, cobalt and copper based on theformation of their complexes with 2-(2-Thiazolylazo)-p-Cresol (TAC) in micellar media of Triton X-100 isproposed. The absorbance spectra were recorded in the range of 500 to 800 nm. The linear concentrationrange for nickel, cobalt and copper in solution calibration sets were 0.05–1.80, 0.10–6.41 and 0.10–6.54μg/ml, respectively. The effects of experimental parameters such as pH, time, concentration of ligand andsurfactant on the sensitivity of method were investigated. The data obtained from the experiments wereprocessed by the partial least squares (PLS), orthogonal signal correction-partial least squares (OSC-PLS)and principle component-back propagation artificial neural network (PC-BPANN). A set of syntheticmixtures of nickel, cobalt and copper was evaluated and the results obtained by each chemometricapproaches were compared with different testing methods. The OSC-PLS method was selected becauseafforded better results than the others. The method was satisfactorily applied for determination of nickel,cobalt and copper in alloy samples. The accuracy was determined using comparing the results to thereference values and also independent analysis by flame atomic absorption spectrometry.